The oxidation method of alcohols into aldehydes or ketones is one of the important methods in the organic synthesis. It is known that alcohols can be oxidized with sodium hypochlorite as an oxidizing agent in the presence of catalytic amount of 2,2,6,6-tetramethyl-1-piperidine-1-oxyl radical (Abbreviated as TEMPO hereinafter) (See J. Org. Chem., 1987, 52, p.2529). Furthermore, it is reported that a N-chloro compound such as N-chlorosuccinimide (NCS) or trichloroisocyanuric acid can be used as an oxidizing agent (See U.S. Pat. No. 5,821,374, and J. Org. Chem., 1996, 61, p.7452).
The present inventors have been extensively studied and found that by using a N-bromoamide compound or a combination of NCS and a compound having bromide ion, oxidation of alcohols effectively proceeds in the presence of a TEMPO derivative as catalyst in an organic solvent. Thus the present invention has been completed.